MORE than half a million Scots would consider moving south of the Border or emigrating abroad if the country becomes independent, an exclusive Sunday Express poll has found.

Sixteen per cent of Scottish voters - the equivalent of 640,000 people - say they would think about moving away if Alex Salmond achieves his dream of breaking up the United Kingdom.

A further 12 per cent say they are unsure of what they would do, while less than three quarters of voters say they would not consider leaving their home country.

There are currently around 500,000 English, Welsh and Northern Irish people living in Scotland, while around 800,000 Scots are resident in the rest of the Britain.

With just over 12 months to go until the referendum, it is clear that a sizeable number of Scotland's five million population would consider fleeing the uncertainty of life in a fledgling separate state.

Younger people aged 18 to 34 and Conservative voters were the most likely to say they would think about emigrating or moving to the rest of the UK.

The potential loss of tax revenue would be a disaster for the first government of an independent Scotland, as well triggering a crash in the housing market and leaving the nation with a catastrophic skills gap.

It would also prove a damaging blow to the confidence and credibility of the SNP.

Our Angus Reid survey of 549 Scottish voters on August 16 - shortly after Scotland played England at Wembley - also found that 66 per cent of people would want to retain British citizenship after independence.

This would create a huge headache for Westminster, although Home Secretary Theresa May has already hinted that Scots could lose their British passports if they back separation.

Asked about the issue of dual nationality in May, she said: "Decisions on UK citizenship are for the UK government.

"Any decision on retention of UK citizenship by Scottish citizens after independence would be affected by future Scottish government policy decisions."

The Scottish Government insists that dual Scottish/British nationality will automatically be on offer after independence.

However, our poll suggests a sovereign Holyrood would be left in charge of around three million people who wish to remain citizens of a foreign nation.

The survey also shows that Scotland is becoming deeply divided by the increasingly bad-tempered independence campaign.

A majority of people (51 per cent) believe the debate is creating new tension and antagonism among families, friends and Scottish society in general.

The tone of the dialogue - which began with last year's Edinburgh Agreement between the First Minister and David Cameron - has become steadily more aggressive in recent months.

Even Olympic cycling hero Sir Chris Hoy was not immune from online abuse from so-called 'cybernats', while the pro-independence Yes Scotland campaign last week claimed its emails had been hacked by "sinister" forces.

In June, Scots Tory peer Lord Strathclyde spoke of the "poison" of Scottish nationalism while former SNP leader Gordon Wilson recently described London and the south of England as a "cancer".

A number of senior figures have appealed for calm, with Glasgow-born broadcaster Andrew Marr last week warning of a growing Anglophobia in Scotland.

According to our survey, 51 per cent of people believe the constitutional debate - the biggest question facing Scots in 300 years - is creating tension and antagonism.

Younger people (61 per cent) and women (54 per cent) were the most likely to have noticed this worrying new social division.

With feelings running so high, it is perhaps not surprising that 28 per cent of people say they feel "engaged" by the referendum debate compared to 20 per cent who say they feel "bored".

The survey also suggests the future of Scotland and the rest of the UK is still in the balance.

Support for independence remains steady at 34 per cent, with backing for the union at 47 per cent - down three points since the last Sunday Express poll in January.

However, a potentially decisive 17 per cent of voters have yet to make up their minds, suggesting the Yes campaign could still mount a remarkable revival.

First Minister Alex Salmond has shown he has no difficulty in confounding the polls, as in 2011 when the SNP began the year well behind Labour and went on to achieve a historic Holyrood landslide.

Any decision on retention of UK citizenship by Scottish citizens after independence would be affected by future Scottish government policy decisions

Home Secretary Theresa May

Women and voters aged 55 and over are the most likely to vote No in the referendum - with support for the Union at a healthy 51 per cent among both groups.

As many as one in five female voters are still undecided, however, suggesting the deliberate targeting of women by Deputy First Minister Nicola Sturgeon could yet pay dividends for the SNP.

The battle is much closer among men, with 41 per cent of male voters planning to vote for independence and only 43 per cent planning to vote against.

However, the move to include 16 and 17 year olds in the referendum may not prove to be much of a coup - our poll shows no spike in support for independence among younger people.

Another intriguing factor exposed by the survey is that a high number of voters look set to ignore their own party's constitutional policy.

Only 55 per cent of SNP voters at the last Scottish Parliament election plan to vote Yes, with more than a quarter - 27 per cent - set to vote No.

Meanwhile, 30 per cent of Labour voters at the last Scottish Parliament election are set to back independence, along with 22 per cent of Lib Dem supporters.

Perhaps unsurprisingly, only four per cent of Conservative voters are planning to vote to break up Britain on September 18 next year.

The final result of note was that only two per cent say they will not vote in the referendum - and all of them are people who did not vote in the 2011 Holyrood election.

This suggests the turnout will be very high, which should provide some relief to the Better Together campaign whose leaders fear a lack of interest could scupper their chances.